Hearing disorders in brainstem lesions

Altered binaural hearing in pre-ataxic and ataxic mutation carriers of spinocerebellar ataxia type 3

Brainstem degeneration is a prominent feature of spinocerebellar ataxia type 3 (SCA3), involving structures that execute binaural synchronization with microsecond precision. As a consequence, auditory processing may deteriorate during the course of disease. We tested whether the binaural "Huggins pitch" effect is suitable to study the temporal precision of brainstem functioning in SCA3 mutation carriers. We expected that they would have difficulties perceiving Huggins pitch at high frequencies, and that they would show attenuated neuromagnetic responses to Huggins pitch. The upper limit of Huggins pitch perception was psychoacoustically determined in 18 pre-ataxic and ataxic SCA3 mutation carriers and in 18 age-matched healthy controls. Moreover, the cortical N100 response following Huggins pitch onset was acquired by means of magnetoencephalography (MEG). MEG recordings were analyzed using dipole source modeling and comprised a monaural pitch condition and a no-pitch condition with simple binaural correlation changes. Compared with age-matched controls, ataxic but not pre-ataxic SCA3 mutation carriers had significantly lower frequency limits up to which Huggins pitch could be heard. Listeners with lower frequency limits also showed diminished MEG responses to Huggins pitch, but not in the two control conditions. Huggins pitch is a promising tool to assess brainstem functioning in ataxic SCA3 patients. Future studies should refine the psychophysiological setup to capture possible performance decrements also in pre-ataxic mutation carriers. Longitudinal observations will be needed to prove the potential of the assessment of Huggins pitch as a biomarker to track brainstem functioning during the disease course in SCA3.

Autism Spectrum Disorder and auditory sensory alterations: a systematic review on the integrity of cognitive and neuronal functions related to auditory processing

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition with a wide spectrum of symptoms, mainly characterized by social, communication, and cognitive impairments. Latest diagnostic criteria according to DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, 2013) now include sensory issues among the four restricted/repetitive behavior features defined as "hyper- or hypo-reactivity to sensory input or unusual interest in sensory aspects of environment". Here, we review auditory sensory alterations in patients with ASD. Considering the updated diagnostic criteria for ASD, we examined research evidence (2015-2022) of the integrity of the cognitive function in auditory-related tasks, the integrity of the peripheral auditory system, and the integrity of the central nervous system in patients diagnosed with ASD. Taking into account the different approaches and experimental study designs, we reappraise the knowledge on auditory sensory alterations and reflect on how these might be linked with behavior symptomatology in ASD.

Contralateral tinnitus and hearing loss due to a tumor at the region of inferior colliculus: illustrative case

BACKGROUND

Subjective hearing loss resulting from unilateral lesions of the quadrigeminal cistern region or inferior colliculus is a rare entity.

OBSERVATIONS

The authors presented the case of a 32-year-old man with a history of 4 months of nonpulsatile tinnitus and 1 month of unilateral sensorineural hearing loss. He was otherwise healthy with no significant previous medical history. Intravenous gadolinium contrast magnetic resonance imaging of the head revealed a lesion at the region of the left inferior colliculus suggestive of a lipoma. The tumor was removed, and the patient had no significant hearing change afterward, with an improvement in tinnitus. The histological examination demonstrated the tumor as a fibrolipoma.

LESSONS

Contralateral subjective hearing loss is an uncommon presentation for a lesion in the region of the inferior colliculus.

Reversible Hearing Impairment Due to Inferior Colliculi Compression by a Pineal Glial Cyst

Pineal glial cysts associated with bilateral hearing impairment are very rare. Here, we present the case of a 13-year-old boy with a pineal cyst, which caused severe bilateral hearing impairment persisting from 6 years of age. When the patient was 6 years old, the bilateral hearing acuity was about 40 dB on audiometry. Upon admission to our otolaryngology department, his audiogram revealed a bilateral worsening of the hearing acuity (80 dB). Magnetic resonance imaging (MRI) revealed an abnormal pineal cyst with tectal compression from the left with hardly normal bilateral brainstem auditory evoked potentials (BAEPs). We obtained informed consent for exploratory surgery and employed the right occipital transtentorial approach for pineal cyst removal. Based on histological examination, we diagnosed a glial cyst of the pineal gland. At 12 months postoperatively, the patient's hearing improved, showing a bilateral hearing acuity of 40 dB on audiometry. Since the auditory pathway has both crossed and uncrossed fibers at the upper pons and midbrain level, compression at the lateral lemniscus or inferior colliculus level can cause bilateral hearing impairment. In the present case, there was a possible slow pineal cyst growth that eventually compressed the upper pons to the midbrain, lateral lemniscuses, or inferior colliculi from the left side, this eventually led to bilateral hearing impairment. These findings indicate that surgery can improve hearing acuity in patients with a pineal cyst associated with progressive hearing impairment.

Clinical characteristics of cerebral hemorrhage with bilateral sudden deafness as the first symptom

OBJECTIVE

To summarize and analyze the clinical data of 12 Chinese patients of cerebral hemorrhage with bilateral sudden deafness as the first symptom and to explore the relationship between cerebral hemorrhage and bilateral sudden deafness.

METHODS

Retrospective analysis of clinical data of patients, including age, clinical manifestations, location of cerebral hemorrhage, hearing loss, and recovery.

RESULTS

The average age of onset in 12 patients was 53.92 years, 9 had a history of hypertension, 7 had a history of stroke, and 6 had typical stroke symptoms. There were 7 cases of basal ganglia hemorrhage; 2 cases of cerebellum hemorrhage; and 1 case of pontine hemorrhage, temporal lobe hemorrhage, and thalamus infarction. The auditory brainstem evoked potential test results of 3 patients were normal, and 5 of 6 patients who completed pure tone audiometry had hearing impairment. Five out of 9 patients had basically or completely recovered hearing.

CONCLUSION

The results showed that patients were mostly middle-aged and elderly with no typical stroke symptoms, and a history of stroke and hypertension increased the risk of hearing loss. The cause of hearing loss in patients with cerebral hemorrhage may be related to the damage of the hearing conduction pathway or (and) the lack of blood supply to the central auditory nervous system. Detecting hearing impairment in time and actively intervening can help most patients to improve their hearing significantly. The degree of hearing damage and recovery is related to the bleeding site, the amount of bleeding, and the timely treatment.

How to detect and track chronic neurologic sequelae of COVID-19? Use of auditory brainstem responses and neuroimaging for long-term patient follow-up

This review intends to provide an overview of the current knowledge on neurologic sequelae of COVID-19 and their possible etiology, and, based on available data, proposes possible improvements in current medical care procedures. We conducted a thorough review of the scientific literature on neurologic manifestations of COVID-19, the neuroinvasive propensity of known coronaviruses (CoV) and their possible effects on brain structural and functional integrity. It appears that around one third of COVID-19 patients admitted to intensive care units (ICU) for respiratory difficulties exhibit neurologic symptoms. This may be due to progressive brain damage and dysfunction triggered by severe hypoxia and hypoxemia, heightened inflammation and SARS-CoV-2 dissemination into brain parenchyma, as suggested by current reports and analyses of previous CoV outbreaks. Viral invasion of the brain may particularly target and alter brainstem and thalamic functions and, consequently, result in sensorimotor dysfunctions and psychiatric disorders. Moreover, data collected from other structurally homologous CoV suggest that SARS-CoV-2 infection may lead to brain cell degeneration and demyelination similar to multiple sclerosis (MS). Hence, current evidence warrants further evaluation and long-term follow-up of possible neurologic sequelae in COVID-19 patients. It may be particularly relevant to evaluate brainstem integrity in recovered patients, as it is suspected that this cerebral area may particularly be dysfunctional following SARS-CoV-2 infection. Because CoV infection can potentially lead to chronic neuroinflammation and progressive demyelination, neuroimaging features and signs of MS may also be evaluated in the long term in recovered COVID-19 patients.

Responding to sounds from unseen locations: crossmodal attentional orienting in response to sounds presented from the rear

To date, most of the research on spatial attention has focused on probing people's responses to stimuli presented in frontal space. That is, few researchers have attempted to assess what happens in the space that is currently unseen (essentially rear space). In a sense, then, 'out of sight' is, very much, 'out of mind'. In this review, we highlight what is presently known about the perception and processing of sensory stimuli (focusing on sounds) whose source is not currently visible. We briefly summarize known differences in the localizability of sounds presented from different locations in 3D space, and discuss the consequences for the crossmodal attentional and multisensory perceptual interactions taking place in various regions of space. The latest research now clearly shows that the kinds of crossmodal interactions that take place in rear space are very often different in kind from those that have been documented in frontal space. Developing a better understanding of how people respond to unseen sound sources in naturalistic environments by integrating findings emerging from multiple fields of research will likely lead to the design of better warning signals in the future. This review highlights the need for neuroscientists interested in spatial attention to spend more time researching what happens (in terms of the covert and overt crossmodal orienting of attention) in rear space.

Auditory hallucinations in cognitive neurology

INTRODUCTION

Different types and localisations of neurological lesions can produce tinnitus and verbal or musical hallucinations (VMH).

METHOD

These symptoms were screened for in 1,000 outpatients at a cognitive neurology clinic, and epidemiological and neuroimaging data were recorded.

RESULTS

Tinnitus was present in 6.9% of the total and VMH in 0.9%. The paracusia group was predominantly female but the difference was not statistically significant. Patients with tinnitus were younger and those with VMH were older than the rest of the sample (mean ages). Hearing loss was more prevalent in the paracusia group (difference was significant in VMH subgroup). There were no intergroup differences in the prevalence of psychotic and obsessive-compulsive disorders, or of leukoaraiosis. Treatment with acetylsalicylic acid was more frequent in the VMH group, whereas other non-opioid analgesics and benzodiazepines were more commonly prescribed to patients with tinnitus. The suspected cause of VMH was dementia with Lewy bodies (n=2, one with vascular disease), Alzheimer disease (n=2, one with vascular disease), isolated cerebrovascular disease (n=3), traumatic brain injury (n=1), and surgical brainstem lesion (n=1). All VMH cases displayed an underlying factor that might prompt this symptom, eg, hearing loss (n=6), a predisposing drug (n=9), and polypharmacy (n=9).

CONCLUSIONS

Treatment with benzodiazepines and non-opioid analgesics was more frequent in the tinnitus group, whereas the VMH group showed a higher prevalence of hearing loss and treatment with acetylsalicylic acid. The causes of VMH were dementia with Lewy bodies, Alzheimer disease, and focal lesions in the mesencephalon, pons, left temporal lobe, or left claustrum.

Auditory spatial deficits in brainstem disorders

PURPOSE

Brainstem disorders seem to negatively influence the central auditory system, causing spatial hearing deficits.

MATERIAL AND METHODS

We tested 11 patients with brainstem lesions due to ischemic stroke (IS), multiple sclerosis (MS), or cerebellopontine angle tumor (CPAT) together with 50 age- and sex-matched healthy volunteers. We used pure tone audiometry (PTAud), brainstem auditory evoked potentials (BAEPs) and the horizontal minimum audible angle test (HMAAT) for 8 azimuths with binaural stimulation.

RESULTS

The chosen patients and the controls had normal or near normal hearing in PTAud. BAEPs interaural wave I-V latency difference was over 7 times longer in the patients group compared to the controls. Additionally, 9 of the 11 patients (81.1%) had abnormal HMAAT results. The biggest quantitative disturbances in HMAAT were present in the CPAT and the MS patients. The sound localization ability in HMAAT was significantly worse in the patients in 0° azimuth in comparison with the controls, and in 45° and 90° azimuth in patients with auditory pathway involvement compared with the ones without the involvement.

CONCLUSIONS

Our study confirms the strong relationship between various brainstem pathologies and sound localization disability and sheds some light on the complexity of the relationship.

Auditory Impairment in Young Type 1 Diabetics

BACKGROUND AND AIMS

More attention has recently been focused on auditory impairment of young type 1 diabetics. This study aimed to evaluate auditory function of young type 1 diabetics and the correlation between clinical indexes and hearing impairment.

METHODS

We evaluated the auditory function of 50 type 1 diabetics and 50 healthy subjects. Clinical indexes were measured along with analyzing their relation of auditory function.

RESULTS

Type 1 diabetic patients demonstrated a deficit with elevated thresholds at right ear and left ear when compared to healthy controls (p <0.01). The elevated auditory threshold was significantly related with HDL-cholesterol, diabetes duration, and systemic blood pressure (p <0.05). Moreover, latencies of right ear (wave III, V and interwave I-V) and left ear (wave III, V and interwave I-III, I-V) in diabetic group significantly increased compared to those in control subjects (p <0.01). Auditory brainstem response was significantly related with GHbA1C and microalbuminuria (p <0.01). Furthermore, distortion product evoked otoacoustic emissions (DPOAE) of diabetes group were statistically significant in right ears at 4.0, 6.0 kHz and in left ears at 4.0, 6.0, 8.0 kHz (p <0.01) compared with those of controls. Diabetic patients demonstrated lower amplitude responses of the right ear than the left ear at 8.0 kHz. Only triglyceride was positively correlated to the hearing impairment defined by DPOAE (p <0.01). There was no significance of transient evoked otoacoustic emissions (TEOAE) between groups. TEOAE was associated with age and GHbA1C (p <0.01).

CONCLUSIONS

Type 1 diabetics exerted higher auditory threshold, slower auditory conduction time and cochlear impairment. HDL-cholesterol, diabetes duration, systemic blood pressure, microalbuminuria, GHbA1C, triglyceride, and age may affect the auditory function of type 1 diabetics.